Data not being retrieved from online mysql server
I am trying to get data from an online database (MySql) via json and want to display it as a ListView. What I have done so far:
Downloader.java
public class Downloader extends AsyncTask<Void,Integer,String> {
Context c;
String address;
ListView lv;
ProgressDialog pd;
public Downloader(Context c, String address, ListView lv) {
this.c = c;
this.address = address;
this.lv = lv;
}
//B4 JOB STARTS
@Override
protected void onPreExecute() {
super.onPreExecute();
pd=new ProgressDialog(c);
pd.setTitle("Fetch Data");
pd.setMessage("Fetching Data...Please wait");
pd.show();
}
@Override
protected String doInBackground(Void... params) {
String data=downloadData();
return data;
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
pd.dismiss();;
if(s != null)
{
Parser p=new Parser(c,s,lv);
p.execute();
}else
{
Toast.makeText(c,"Unable to download data",Toast.LENGTH_SHORT).show();
}
}
private String downloadData()
{
//connect and get a stream
InputStream is=null;
String line =null;
try {
URL url=new URL(address);
HttpURLConnection con= (HttpURLConnection) url.openConnection();
is=new BufferedInputStream(con.getInputStream());
BufferedReader br=new BufferedReader(new InputStreamReader(is));
StringBuffer sb=new StringBuffer();
if(br != null) {
while ((line=br.readLine()) != null) {
sb.append(line+"n");
}
}else {
return null;
}
return sb.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
if(is != null)
{
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
}
MainActivity.java
public class MainActivity extends Activity {
String url="http://bookvilla.esy.es/book.php";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ListView lv= (ListView) findViewById(R.id.lv);
final Downloader d=new Downloader(this,url,lv);
d.execute();
}
}
when i run my app in app. I get a toast message saying "unable to download data" which is on line 35 of the Downloader.java class. So I am assuming that the data I am getting from the database is null ... but why is it ...
$ con = mysqli_connect ($ host, $ u_name, $ pwd, $ db) or die ('Unable to connect'); if (mysqli_connect_error ($ con)) {echo "Failed to connect to database" .mysqli_connect_error ();
}
$ query = mysqli_query ($ con, "SELECT * FROM playerstb"); if ($ query) {
while ($ row = mysqli_fetch_array ($ query)) {$ flag [] = $ row;
} print (json_encode ($ flag)); } mysqli_close ($ con);
above is my php file
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1 answer
Not sure how to fix your problem, but I used a different method:
db_config.php:
<?php
define('DB_USER',"root");
define('DB_PASSWORD',null);
define('DB_DATABASE',"phoneshop");
define('DB_SERVER',"localhost");
?>
db_connect.php:
<?php
class DB_CONNECT {
private $con = '';
function __construct() {
$this->connect();
}
function __destruct() {
$this->close();
}
function connect() {
require_once __DIR__ . '/db_config.php';
$this->con = mysqli_connect(DB_SERVER , DB_USER , null , DB_DATABASE) or die(mysqli_error());
return $this->con;
}
function close() {
mysqli_close($this->con);
}
function query($query){
return mysqli_query($this->con, $query);
}
}
?>
And then I made this file to get the data:
<?php
$response = array();
require_once __DIR__ . '/db_connect.php';
$db = new DB_CONNECT();
$result = $db->query('SELECT * FROM products') or die('error');
if (mysqli_num_rows($result) > 0) {
$response["products"] = array();
while ($row = mysqli_fetch_array($result)) {
$product = array();
$product["pid"] = $row["pid"];
$product["name"] = $row["name"];
$product["price"] = $row["price"];
$product["description"] = $row["description"];
array_push($response["products"], $product);
}
$response["success"] = 1;
echo json_encode($response);
} else {
$response["success"] = 0;
$response["message"] = "No products found";
echo json_encode($response);
}
?>
And then from android studio:
Call:
private String url_all_products = "http://10.0.0.10:8012/onlineShop/get_all_products.php";
//ip of the server or 10.0.2.2 if in emulator
ContentValues params = new ContentValues();
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
And the analyzer:
public class JSONParser {
static JSONObject jObj;
static String json;
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public static JSONObject makeHttpRequest(String url, String method, ContentValues params) {
// Making HTTP request
try {
final OkHttpClient client = new OkHttpClient();
Request request;
// check for request method
if (method.equals("POST")) {
// request method is POST
MediaType contentType = MediaType.parse("application/x-www-form-urlencoded; charset=UTF-8");
String content = "";
for (String key : params.keySet())
{
if ( !content.isEmpty())
content += "&";
content += key + "=" + params.get(key);
}
RequestBody body = RequestBody.create(contentType, content);
request = new Request.Builder().url(url).post(body).build();
}
else {
// request method is GET
request = new Request.Builder().url(url).build();
}
final Response response = client.newCall(request).execute();
json = response.body().string();
} catch (IOException e) {
e.printStackTrace();
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e ){
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
Adding this to gradle:
compile 'com.squareup.okhttp3:okhttp:3.4.2'
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